ST1100 starving for fuel?

[RickA]

Cruising along at about 80mph during my morning commute my ST1100 started losing power. I rode about 1 more mile before I pulled over and the bike ran very rough (1 or 2 cylinders) and died. It felt like it was starving for fuel. The tank was about ? to 1/3 full and I had been on the road for about 40 miles. Temperature should not have been a factor since it was about 28 deg F when I stopped (thanks for Gerbing electric clothes!). I opened the fuel cap and did not hear a rush of air but it?s pretty noisy on the side of the freeway. The bike started again after a few minutes, ran a little rough (the choke smoothed it out) and then ran normally. I decided to go back home and at about 40 miles it starting starving again and finally died.
I got home and ran lots of tests. Fuel pump is putting out about 1-1 ? PSI and 1800cc per minute. Ran the pump for ? hour unloaded (with very good flow) and ? hour more into a pressure gauge (1 ? PSI). So the pump seems OK. I just rebuilt the Fuel cutoff about 5,000 miles ago. Still, I tested it by applying suction and it opens at 1 to 2 inches of vacuum. Also checked the fuel cap vent line which is open and vented near the kickstand.
The vent action on the fuel cap seemed ?sticky? so I opened, cleaned, and re-assembled it as shown on the other LiST.
By the way, the bike is coming up on 124,000 miles now and this is my first failure.
I?m thinking that the fuel cap was not venting correctly. But I?m a little bit afraid of the bike now. Some of my commute involves a toll road with no shoulder to pull off, I got lucky this morning.
I?m thinking of replacing the pump, cap and bypassing the fuel valve just to feel better but that?s LOTS of ca$h.
What do you folks think?

Rick

 

[Killtimer]

At 28f I bet you had some carb icing if there was any humidity at all.

 

[George]

Bypassing the vacuum cut-off is free. Fiddling with the gas cap is free. 2 chances out of three that one of those will fix it. Leave the fuel pump til last.

O, the fuel pump can be disassembled and "unstuck" too, if that's the problem. I did it to STick two years ago and have had no problems since.

 

[Mark]

My vote goes to Steve's suggestion... Carb icing.

28F and you're in wet SoCal...

 

[BigTom]

My guess is fuel switch/fuel filter. In fact, I'm guessing fuel valve.

I'd bypass it and run a while to see. Then I'd change the filter.

 

[RickA]

Steve and Mark, I hadn’t thought about carb. Ice. Hmmm, maybe?

George, I’d love to do more troubleshooting but the roads I commute on are very unsafe for a break-down. Maybe I’ll try a different route for a while to do some testing.


Rick

 

[RickA]

My guess is fuel switch/fuel filter. In fact, I'm guessing fuel valve.

I'd bypass it and run a while to see. Then I'd change the filter.

The filter and fuel valve are very new, but they could still be a problem. I may see if it happens again and then do the bypass.

By the way, I'm heading down to the Yuma prison run again next month. Hoping for good weather and having my fuel problem sorted out!

Rick

 

[forgitaboutut]

got a same type of prob with my triumph,but not weather related...I'm goin more toward petcock or ignition coils in my case....
let us know what you find!

 

[RickA]

Rick--I also vote for the likelihood that your problem was carb icing. I can't find in your post or profile what year your ST1100 is. Early models had two hoses directing fresh air to the carbs while later models dropped that to one hose because of carb icing problems when too much cold damp air was fed to the carbs.

Do you recall how many hoses you have? You can readily tell by removing the top shelter. If you have two, I would remove one. I have a 2001 model and the right side one is the one remaining but I would imagine it wouldn't matter which side you leave.

I wouldn't touch anything else that has been suggested until you resolve the carb ice possibility.

C.B.

My ST is a 1999 and it only has one hose on the right side.
I have already disassembled the fuel cap and cleaned it. I don?t plan on making any other changes until I drive it some more.
I would sure feel better if I new exactly what caused the problem!
Since I had the covers off to check the pump etc I decided to do a valve adjustment so I won?t be riding it for a few days while I wait for shims. I might change the plugs also but the Iridiums that are in there only have 90,000 miles on them so I may wait ?till they have 100,000 

Rick

 

[ormctraveler]

Hi Rick,
The symptoms are nearly identical to a failure I had with the '83 Gold Wing. Surprisingly, it was the main fuse which had burned but not completely separated / broken. It was the "dogbone" type and vibration was causing the intermittent power losses and not firing on all four feelings - like it was starving for fuel. Fortunately the fuse never completely separated and I was able to ride it home all the way from Valley of the Rogue State Park. I haven't checked to see if my ST has the same type of main fuse but curiosity will have me in the garage in the a.m.
Take care,
Dennis

 

[RickA]

Here is a quick follow-up.

I have put about 500 miles on the bike since my problem a few weeks ago and the bike is running great with no further symptoms.
I did disassemble the gas cap and cleaned out some slime but that’s about it.
However it hasn’t been nearly as cold as the day it acted up.
While I was working on the bike, I did a valve adjustment (2nd one in 124,000 miles) and put in a new set of spark plugs.

Rick

 

[Mark]

I did a valve adjustment (2nd one in 124,000 miles) and put in a new set of spark plugs.
Rick

Pretty aggressive maintenance schedule there, Rick... are you sure you can keep up this blistering pace?
Did you have to swap any shims?

Glad to hear that beauty is back on the road too!

Mark

 

[RickA]

I’m really not that lazy about my maintenance Mark, but this bike just doesn’t need much

I have checked the valves several times but only changed shims at about 70,000 miles and now at 124,000. I have never been out of tolerance, just at the tight end.
I had to buy a couple of shims the first time and two more this time. I was also able to move the existing shims around to optimize all of the cylinders. By the way, my clearance has always become tighter.

Rick

 

[Hellbilly]

Still sounds like carb ice to me. With any humidity in the air at all you will get that. Had it happen between 25 & 28 degrees on my Harley (and so did everyone else) in Georgia at those temps. You could run your hand under the air filter and come up with a glove coated in frost from the carb. It would happen toward the end of our twelve mile commute to work.

 

[RickA]

Kind of hope it was ice, but then again I would feel lots better if I could find a hard failure and fix it. I have ridden in the rain twice since the problem but it was much warmer (low 40s) with no hint of a problem.
So, I'm back on my quest to wear this bike out.

Rick

 

[Hellbilly]

Kind of hope it was ice, but then again I would feel lots better if I could find a hard failure and fix it. I have ridden in the rain twice since the problem but it was much warmer (low 40s) with no hint of a problem.
So, I'm back on my quest to wear this bike out.

Rick

Well, if you get a chance to duplicate the problem in the same temperatures, try to get a look at the carb under the cleaner as soon as you can. If you see frost on the bowl or around the intake portion, I would bet you found the problem.

+1 on finding a hard failure, but that usually ends up lightening your wallet. I would try it on mine for you as it's been somewhat cold in the mornings here in Denver, but at this altitude there's almost zero humidity and I have fuel injection on my '03.

Good luck.

 

[Don-STOC237]

Carb icing gets my vote too. Temps anywhere from about 15F to 50F with high humidity can make it happen, usually at the lower end of that scale. You're describing the symptoms of it to a tee. Very hard to track down too because as soon as you stop, the engine heat melts the ice blockage and you're on your way again.

 

[RickA]

Dang, my problem is back! Bike died 3 times during the commute this morning. Temperature was about 35-40 F with high humidity. Total commute this morning was about 50 miles. The first incident was at about 25 miles then about every 10 miles after that
I left the gas cap loose after the first incident but it still died 2 more times. I guess it could be ice, but what now??
Do I leave the bike at home when it is cold and humid?
I love the bike and it?s been great for 125,000 miles but I REALLY hate breaking down.

By the way, I?ve put about 1000 miles on the bike since I had the first problem without any issues but this is the coldest commute I?ve had.

I?ll see if I make it home ok later when it is much warmer?

Rick

 

[Killtimer]

Dang, my problem is back! Bike died 3 times during the commute this morning. Temperature was about 35-40 F with high humidity. Total commute this morning was about 50 miles. The first incident was at about 25 miles then about every 10 miles after that

Something that worked marginally well for me when this happened was to use a rag to close off the end of the snorkel tube that feeds cold air down to the carb area. IIRC the intake is on the right side of the bike fairly high up and accessible without pulling plastic. HTH

 

[John OoSTerhuis]

Rick,

The quick fix for carb icing is to simply plug the fresh air snorkle(s*) intake(s) at the front of the bike with something (rag, paper towel, etc). Then the carbs only get warmer and drier air from the engine 'V.'

[edit: I see my friend STeve beat me to it while I was typing ]

John

*Some ST1100s have two snorkles.